As shown in FIG. 1, a conventional ceiling fan motor cover 10 of the prior art is provided with a plurality of flange fixed through holes 12, which are arranged in a specific pattern that enables four or five fan blades to be mounted to the same ceiling fan in accordance with the preference of a consumer. In the process of installing the fan blades, each blade of the ceiling is mounted to the two through holes. If the fixed number of the fan blades is four, the fan blades are then mounted in a pattern designated as "A". If the fixed number of the fan blades is five, the fan blades are mounted in a pattern designated as "B", as shown in FIG. 1. Such structural design as described above has several shortcomings, which are elucidated hereinafter.
The weight of the motor cover 10 is not evenly distributed in view of the fact that the flange fixed through holes 12 are not evenly distributed, thereby causing various portions of the motor cover 10 to have different centrifugal forces at the time when the motor cover 10 is caused to rotate. As a result, the motor cover 10 tends to wobble and makes a lot of noise when in operation. Such a prior art motor cover 10 has a relatively short service life span.
The flange fixed through holes 12 of the motor cover 10 are so distributed that they often make the installation of the fan blades rather confusing and time-consuming. In other words, the installation of the first fan blade must be started from a specific flange fixed through hole 12 so that the rest of the fan blades are mounted sequentially in a correct pattern.
Another kind of the motor cover of the prior art is shown in FIG. 2, in which the motor cover 14 is provided with a plurality of flange fixed through holes 16, which are arranged in two groups on the two circles having different diameters. Each of the two groups is arranged in a predetermined pattern. If four fan blades are to be mounted to the motor cover 14, the fan blades are mounted respectively in the flange fixed through holes 16 forming a pattern designated as "A". On the other hand, if five fan blades are to be mounted, the fan blades are then mounted in the flange fixed through holes 16 forming another pattern designated as "B". The motor cover 14 of the prior art has the following shortcomings.
The flange fixed through holes 16 of the motor cover 14 are so unevenly distributed that the weight of the motor cover 14 is thus distributed unevenly. As a result, the motor cover 14 wobbles when in operation. It is also rather time-consuming for a worker to mount the fan blades.
The flange fixed through holes 16 are formed in two groups, which are distributed on the circles having different diameters. As a result, the mounted fan blades will have different lengths, thereby undermining the efficiency of the ceiling fan to generate a current of air for ventilating or cooling.